medwireNews: The number of dissected lymph nodes in patients with clinically node-negative (cN0) oral cavity squamous cell carcinoma (OCSCC) correlates with overall survival (OS), suggests a review of a US patient population.

“Based on this analysis, thorough surgical neck evaluation should be advocated for cN0 patients with OCSCC”, recommend Chiaojung Jillian Tsai and co-workers, from Memorial Sloan Kettering Cancer Center in New York, USA.

The team identified 7811 patients diagnosed with cN0 OCSCC in the USA between 2004 and 2012 who received definitive surgery without neoadjuvant treatment. The patients had a median node count of 23, the researchers say, and 77% of patients were N0 on pathological examination.

The patients were followed up for a median of 48.3 months and had a median OS of 92.2 months, the authors write in JAMA Otolaryngology–Head & Neck Surgery.

Multivariable analysis indicated that patients with more than 24 nodes dissected had a significantly lower risk of mortality than those with 24 or fewer nodes resected, with a hazard ratio (HR) of 0.82. OS was also significantly better in patients who received at least 5000 cGy of adjuvant radiation than those who did not (HR=0.84).

By contrast, mortality was significantly more likely in patients aged 60 years or older versus their younger counterparts (HR=1.30), in those with greater comorbidity (HR=1.57) and more advanced tumour stage (HR=1.54–2.25 for pT category 2–4 vs 1), and in those who had Medicaid or Medicare versus private insurance (HR=1.52).

Using bias-adjusted concordance probability, the team calculated a multivariable c-index of 0.66 for the relationship between OS and dissection of more than 24 nodes, where 1.0 would equal perfect concordance.

“Because OCSCC is treated primarily by curative surgery, it is imperative to analyze this disease as a separate entity and account for tumor depth of invasion, a crucial prognostic factor”, the researchers emphasize.

“Furthermore, since locoregional recurrent OCSCC patients have poor salvage outcomes, it is appropriate to use a more stringent nodal yield than previously described.”

Jon Mallen St Clair, from the University of California–San Francisco in the USA, notes in an accompanying comment that the findings follow a randomised clinical trial indicating that elective neck dissection in early oral cavity cancer is associated with better survival.

However, he cautions that the demonstrated association between node dissection yield and OS “does not necessarily prove that removing more lymph nodes is the cause of improved survival.”

Noting that other variables such as achievement of negative margins, cancer centre patient volume and insurance status have previously been linked to survival in head and neck cancer, the commentator suggests that improved survival may be evidence of improved adherence to clinical guidelines.

Jon Mallen St Clair concludes: “These studies suggest that developing clinical best practices and improving guideline adherence may decrease variation in care and improve outcomes, and that developing a standard of care for a quality neck dissection may represent an important part of future clinical guidelines.”